Inside-frosted incandescent



March 9, 1937. R. YAJIMA INSIDE FRQSTED INCANDESCENT ELECTRIC LAM 1 BULB Filed Odt. 22, 1934 Fii {r0 Ya) 1m cu INVENTOR 12 ATTORNEY.

Patented Man. 9, 1937 UNITED STATES INSIDE-1 808111) INCANDISGIN'I.

' ELECTRIC LAMP BUIB Blniiro Yaiima;

Sh ns assignor to Todendenkyu Tokyo, Japan n-Im. m. mu; Kablllhlfl m Application October 22,1934, Serial No. 748,681

- In Japan October 31, 1983 2 Claims. (CI. 41-43) This invention relates to an inside-frosted in-.

candescent lamp bulb figured by difierent intensities of frosting and has for its object to produce a bulb having a delightful appearance and being 5 free of any tendency to produce a dazzling effect when lighted.

The half-frosted bulb hitherto used has the frosted and transparent areas separated by the boundary line between them while the frosted weaken the bulb, and which is then subjected to an acid-proof material applied to the frosted sur- 20 face of the bulb to form any desired figure or spot, after which the bulb is once more subjected to a second frosting treatment and finally washed with water or other suitable means to remove the acid-proof material.

If so desired, the process'may be modified in such a manner that the bulb is at first figured by an acid-proof material and then subjected to the first frosting treatment, thereafter washing out the said acid-proof material, and finally o frosting the entire surface.

The arrangement of the varied areas consisting of different intensity of the frosting produces an eifect which is devoid of any dazzle. 'Ihe dimensions of the areas may be adjusted by den- 35 sity of the frost liquid and the frosting time. As a subsequent frosting reinforces the weakened portions resulting from the first frosting, no further reinforcing treatment such as heating or chemical treatment is required.

40 Ifitisdesiredto havethefigureareasappear in a crystalline form, it is contemplated to separate out the peculiar crystal of such a material on the inner surface of the bulb as is stable to the action of the frosting liquid.

hr this purpose, the said material, for instance, may be a supersaturated solution of sodium phthalate, which is first applied on the inner surface of the bulb. Then upon cooling the bulb for a' short time, the distinct crystals of sodium phthalate are separated out. After the bulb thus treated has been frosted, said crystals are washed out with water, whereby'the figures in the peculiar crystalline form will appear. If the brilliancy of the bulb obtained is too strong, the bulb may be frosted once more after the washing out of the crystals. These crystalline figures can also be formed by means of sublimation of -haphthalene or phthalic acid.

Thus the incandescent lamp bulb according to the present invention produces an excellent diffusion of beautiful light and entirely prevents any dazzling effect from the bulb because of'the difierence in brilliancy produced by different intensityofthefrostinginthespacedareas.

The drawing shows a front elevational view with a portion broken away of an incandescent lamp according to the invention in which I denotesthe part twice frostedandfthepartfrosted but once.

Having now fully explained the nature of invention. what I claim is:

1. Thehereindescribedprocessoffrosting the inside surface of an incandacent lamp bulb to produce a crystalline form, which process consists in apply n a supersaturated solution of sodium phthalate to the inner surface of the glass bulb,

thereaftercoolingthesametoseparatethecrys-- frosting and'to frost the clear surfaces covfirst eredbythecrystalsifmingthefirstfrostlng. 

